1. Field of the Invention
The present invention generally relates to a method of forming measuring targets for measuring the dimensions of a substrate, in particular, to a method of forming measuring targets for measuring the dimensions of a substrate in a substrate manufacturing process.
2. Description of Related Art
In recent years, the designs of both electronic products and the substrates adopted therein are going towards lightness, slimness, shortness, smallness, multifunctionality, and especially, high circuit density. In an existing method for fabricating a substrate of high circuit density, a hard base layer is provided as the core and circuit layers are then built up outwards. According to this method, dielectric layers and circuit layers are alternatively formed on the top and the bottom of the hard base layer, and the circuit layers are electrically connected by forming vias in the dielectric layers and plating copper in the vias. Because such a substrate has very high circuit density, the positions of the circuit layers and vias have to be very accurate. However, during the fabricating process of such a substrate, the dimensions of the base layer, the dielectric layers, or a solder resist (SR) layer may be changed by heat or other factors so that the accuracy thereof may be reduced and accordingly the process yield may be affected.